WG 25K7197 New Wei Ya Chassis - UPDATE: Might have just fried it

[MaxAsh]

Hello all - new guy learning the ways of the arcade world. Been reading a lot, so I think I'm on the right track, but I want to make sure before moving forward. If you have a moment and could provide some quick advice, I'd appreciate it. Thanks! Here's my situation:

Short version of my story: picked up an Ultimate Mortal Kombat 3 game (built into a MK1 cab) that plays blind. The chassis was completely missing from the WG K7000-series monitor, which was still in place. To test the game itself, I hooked it up to a Hantarex Polo 25" from another cab temporarily. Worked beautifully, so I knew the game output video just fine.

I threw a Wei Ya 25" universal chassis into the existing WG monitor after testing the yoke readings to make sure they were within range. I didn't go through the "Americanize" process for the Wei Ya I've seen Ken Layton describe, since I wanted to just wire it up with some splicing/rigging to find out if the monitor itself even works. I figured if it did, I'd go ahead and setup the chassis permanently. I'll go over the problems, what I've done, and where I'm at below:

I fired it up, and the monitor came to life immediately - good sign. I noticed 3 problems with the image immediately. 1) upside down 2) backwards 3) out of phase/sync and shaky.

I noticed the Wei Ya chassis had two separate Yoke hook-up locations side by side, so I moved it to the other yoke hook-up. This solved issue #1, flipping the screen. Next, I cut the yoke connector in half, and reversed the Red/Blue positions. This solved issue #2.

My final issue is (I think) a sync issue. (See Pics) The UMK3 output has the white sync wire in pin position 5 instead of pin position 6. The Wei Ya board has no pin 5 for the RGBGrSync pinout. To resolve this, I simply spliced the white sync wire to position 6 on the connector at the chassis end. It's the only sync pin available, so I would think it would work. Please see the picture links for details.

Is the problem simply that I need to "Americanize" (in Ken Layton's terms) the Wei Ya chassis, replacing it with a 6-pin connector, and moving my sync back to position 5? I thought that sounded odd, as I would think the Wei Ya not having a pin there would mean that position has no trace or connections to it. I can post additional pictures if it helps. Thank you in advance everyone!

[MaxAsh]

Uh oh. This just got a whole lot worse. So I figured I'd play around with the H and V holds, which stabilized the image a little, but not by much. I was playing around with them for about 4-5 minutes when I noticed a burning smell. I checked everything, didn't notice anything awry, but the tall white (cement?) resistor was radiating a lot of heat. That's where I think the heat was coming from anyway. So I reached over to cut the power, and a second before I did there was a Pop/Pffft sound and a huge cloud of white smoke came out of the chassis area.

Did I just fry it? There's an isolation transformer all setup (can see it blurry in the background of one of the pics) so I'm pretty sure that's okay. Did I just lose this chassis? Flyback?

Side note: is that smoke unsafe, I've got the room blowing air outside at the moment, but I breathed in a heck of a lot when it first puffed out.

EDIT: Adding pics of Isolation Transformer/wiring. I found another Ken Layton Post where he discusses a Wei Ya chassis with a Hantarex Polo. He mentioned that the isolation transformer should ONLY have the monitor power coming off one side, not other things (coin door, marquee lights, etc). Looking at mine, I see several connections coming off the left side. The yellow wires appear to trace to the coin door area. I followed the (4) purple wires and found that 2 went up towards the marquee area. Two others ended up joining up with leads coming DIRECTLY off the switching power supply (see pic #2... wire tape connector). My monitor is powered by the latter connections... the wire tapped switching PSU AC + Isolation transformer connections.

Is this causing the problem perhaps?

[Ken Layton]

What model of Wei-ya chassis did you get?

[MaxAsh]

It was supposed to be a 25" model, ordered from dirt cheap trading. Just looked closer... it's 429H... 29" model. But, according to their website, this should work as long as my yoke readings are in range 6-12ohms (vert), and higher than 1.5 ohms (horiz). My readings were 10.1 and 2.1 respectively if that helps. Thanks

[Ken Layton]

I have no information on any Wei-ya models above 25". The only information I have is just the picture of the model label you posted.

I *think* this chassis needs to be run from an isolation transformer. That might be what happened to you. Be sure to remember this: if you have a chassis designed for a 29" tube and you're using it on a 25" instead, then the picture is likely going to be way too big and probably will not be able to adjust small enough to fit your 25" tube.

A great many Mortal Kombat cabinets were shipped with the isolation transformer wired wrong. Many cabinets had a Wells-Gardner U5000 monitor installed which does not need isolation so the problem was not noticed at the factory. Only the monitor should be powered by the output of the isolation transformer. Any other line voltage AC powered stuff (light fixture, switching power supply, bill acceptor, etc) should be connected to the input side of the isolation transformer.

[MaxAsh]

Thanks for the quick replies Ken! The information the seller posted says the chassis can be used for 25" and 29", which seemed odd to me. They did update their listing to state clearly that an isolation transformer is required, but I assumed since I had one I was okay. What I really don't  understand is what the ac terminals on the switching power supply would be connected with two of the wires coming off the isolation transformer, then going to the monitor chassis. It's as if the isolation transformer is feeding both the monitor and the switching psu on the same output? That seems crazy, or am I wrong?

From what I can tell (going to really look closely tomorrow) there are 4 wires coming off the upper part of the isoT. 2 go to the monitor (and switching psu) and two go up to the marquee (which is disconnected). I think the coin door lines are coming off the lower side of the iso... not sure.

So what are the odds I fried the chassis? Despite the puff of white smoke and smell, the monitor was still working when I shut down the power. Is it possible I might have just blown the resistor? Just trying to figure out my next step. I do have the option of just pulling the monitor completely and replacing it with a hantarex polo 25 I have, which doesn't need an isolation trans I think. Ideally, I'd like to get this WG to work though.

[ed12]

i just ran a search on that chassic
it turn's out in our monitor threads there is some info there but they are all pointing
toward's iso trans must be used

ed

[Ken Layton]

It's hard to say what happened for sure without a schematic. It's possible something is cooked, but you'd need to pull the chassis and eyeball it good.

You might have blown some diodes, resistors, capacitors, or transistors. You'd need to whip out your test equipment and start checking components.

[grantspain]

that could be a shorting deflection yoke,the picture has locked perfectly at the top.

i had an almost identical issue on a wg7000 a few months back,I am trying to find a photo as its very similar.
The problem with this kind of fault is that you won't be able to read the short even using an inductance meter as it almost certainly shorts only when voltage is applied.

the chassis is an almost perfect match for the deflection yoke spec and in any case you would have to very far out to get issues anyway,for instance i test nanao ms9 on sanwa es31 yokes and k7000 on hantarex polo 1 yokes.

if we had a schematic for that chassis and the resistor number that smoked then we could probably id the issue,although a ceramic resistor would most likely be in the power regulation circuit rather than the deflection circuit so atm i am just guessing

an iso should power the monitor only so you should consider rewiring

[MaxAsh]

that could be a shorting deflection yoke,the picture has locked perfectly at the top.

The image I posted might be a little misleading as it is a frozen representation. The effect I was seeing was more of a wavy, moving, distortion. The picture just happened to be taken when top/bottom appeared clearer. I'll keep that in mind though, if I end up still being able to use this chassis.

It's hard to say what happened for sure without a schematic. It's possible something is cooked, but you'd need to pull the chassis and eyeball it good.

You might have blown some diodes, resistors, capacitors, or transistors. You'd need to whip out your test equipment and start checking components.

I'll discharge and pull it today and start taking a look. I'll post some pics as well. I'm still relatively new to this, so my experience with board-level work has primarily been replacing caps/resistors/general soldering. I'll google (and search the forums) for testing procedures for my situation. If anyone has a direct link, feel free to toss it my way to save me some hunting, thanks!

Just to double-check, consensus seems to be that the most likely culprit is that the isolation transformer is not dedicated solely to the monitor, correct? Based on comments, the fact that the iso leads for the monitor are shared with the switching power supply is a big no-no and easily causes a blow like this?

I'm also going to disassemble a bunch of the power wiring and trace it out (taking pictures/notes). I found Bob Roberts explanation on AC wiring, but it appears to be more of a from-scratch setup, slightly different from mine. I'm sure it's the same principle setup, but I'll double check with you guys as I go. Thanks all, more to come in a bit...

[MaxAsh]

Because it never hurts to document as much data as possible for future viewers - here are some images of the only documentation that came with the Wei Ya 429H. It's not fancy, but it's something. R804 is (I think) where the heat and eventual smoke came from. C918 and the 2A / 6A fuses all look good. I'll have to pull it to see much more. EDIT: Correction - C918 is blown.

[MaxAsh]

Pulled the chassis, took several pictures (see two of them below). In the close-up, you can see the blown C918 large capacitor, and just to the left the tall white resistor. If you look closely, you can see the crack running down from the top to bottom, which I'm assuming is an indicator of it being blown (and probably the source of my white smoke earlier?). All I can read on the side of it is that it's 25W, not sure beyond that. I assume I can scoop these up at mouser or digikey, etc.

I also included an aerial shot of the whole chassis for reference. You can't tell from that aerial shot, but none of the other capacitors appear to be bulging. I'll do some overall testing now and update this post in a bit. Thoughts/comments so far? Any special advice on what/where to test besides the basics is welcome. Thanks

EDIT: Update - Just went through and tested a lot of components. Everything seems pretty good aside from:

 

• Tall white R804 resistor that's cracked (test showed a negative reading that then steadily climbed into positive and just kept climbing in reading)
• Large capacitor shown in the image aka C918 (clearly blown in the image)
• Possibly transistor on the far bottom of the aerial chassis image, a little to the right of the blown large cap. Labeled Q801. When I tested the transistor, I got a ~0.50 reading on one outer leg, but no reading on the other. I tested the other transistor (near the flyback area) and both legs read about 0.50.

So far everything else seems okay, continuing to test just in case. I'm getting continuity and proper resistance testing on all the other components so far. Am I correct in my assumption that the transistor with the non-reading on an outer leg is bad now?

[MK3FAN]

That big, blown capacitor is most likely the filter cap. I would start with replacing it, the large, tall, vertical ceramic resistor next to it and see what that does for you. I didn't see, but did you test your HOT?

[grantspain]

blimey a mains filter cap exploded,only ever seen that when ac input voltage is way too high

[MaxAsh]

That big, blown capacitor is most likely the filter cap. I would start with replacing it, the large, tall, vertical ceramic resistor next to it and see what that does for you. I didn't see, but did you test your HOT?

Assuming I'm testing the right things (being new to this), I believe I tested both transistors (3 pin just to the left of the big blown capacitor and 3 pin over near the flyback area). I'm not sure which is the HOT, but I can tell you the one closest to the large blown cap has a leg with no reading (leg closest to the cap). The other leg is fine @ 0.50. The transistor near the flyback is fine on both legs.

Some more pictures and info regarding the power setup. I can draw a full diagram if necessary, but I think laying it out here in text should work, supported by the images attached. I'm starting to wonder if this is even setup as an isolation transformer. The look of it doesn't seem to match anything I'm seeing in setup videos, etc. Feedback is welcome, thanks all!

Voltage Readings
- Monitor Power:  131.4 V
- Marquee Power:  131.4 V
- Switching Power Supply:  132.4 V
- Coin Door Lights/etc:  6.1V

DC off switching PSU is good (12.8 / 5.0 as it should be)

Wiring Details

As you can see from the pictures, the transformer is sitting on top of the incoming power block. In one image, labeled "Transform_RightSide", you can see the incoming AC cord, fuses, and also the outgoing wires to the cabinet power switch (black & white with stripes).

On one side of the transformer (RightSide in pictures), I have a big bundle of wires that enters a large connector block. The black and white (striped) wires that I assume are the power switch wires mentioned above also go into this large connector block. Exiting that block are only 4 wires, all of which appear to go to the switch. (black, white, blue, yellow).

On the other side of the transformer (LeftSide in pictures) I see several things.

- First, coming out of the power block area are two yellow wires. One yellow wire goes directly to the coin door area. The other appears to pass thru the bottom area of the transformer, then continue to the coin door area as well.

- Coming out of the top area, as shown in pictures, are (4) purple wires. They enter a 4-pin connector. Two of the wires (the two in the center of the connector) go directly to the Marquee lights. I have disconnected the marquee lights since the initial problem occurred, but testing shows 131.4V at the marquee connector.

  The other two purple wires leaving the transformer (outer wires coming out of the 4-pin connector) travel a short distance and are spliced together with the two wires coming off the two AC terminals on the switching power supply (see pic labeled "Monitor_SwitchPSU-merge"). And then continue on to the monitor power connector.

Assuming I'm interpreting this all correctly, here's what that means: The transformer in question is outputting directly to the cabinet power switch on one side. On the other side I have a lower connection outputting 6.1V to the coin door area. On the upper connection I have:

131.4V existing on (4) wires and feeding three things: Monitor, Switching PSU (share two wires out of transformer through splice), Marquee light (2 wires to itself).

So here's the big question: is this even an isolation transformer, or is this just a transformer and this cabinet has no isolation transformer? If it IS an isolation transformer, can I peel back the paper covering and rewire it in a way that will isolate the monitor, but still feed power to the marquee and switching PSU?

Thank you, apologies for the long post, but I wanted to include as much detail as possible. If additional info is needed, please let me know. Thanks to everyone for their help!

[MaxAsh]

blimey a mains filter cap exploded,only ever seen that when ac input voltage is way too high

With all the outputs from the power/transformer area being 131.4 ~ 132.4 V , guessing that's spot on.

Edit: Sidenote... I have a second cabinet (Time Killers) which contains a Hantarex Polo 25". Looking at the power setup and wiring it is 100% identical to the Mortal Kombat wiring. Right down to the Switching PSU and Monitor being fed off the same wires from the transformer area. The big difference, based on what I've read: Hantarex Polo 25 doesn't need an isolation transformer. This explains why, when waiting for my chassis to arrive for the MK cabinet, when I tested the video output of the game to the Hantarex Polo, everything was perfect. Live and learn. /end Sidenote

[Ken Layton]

Blimey a mains filter cap exploded. Only ever seen that when ac input voltage is way too high.

Or when a chassis that needs isolation is run without an isolation transformer.

The exploded main filter capacitor will have to be replaced and I bet one or more of the four diodes next to it are shorted. Possibly a blown foil trace on the foil side of the board. Transistor Q801 is the B+ regulator and it should get tested to see if it's shorted along with transistors Q802 and Q803 (also part of the power supply circuit.

The big resistor is generally 140 or 160 ohms @ 25 watts and should be replaced if it cracked.

Pdf page 40 (3-4 original page number) of the manual shows cabinet wiring of Mortal Kombat:

http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Mortal_Kombat_1_%2816-40025-101_July_1992%29.pdf

[MaxAsh]

Great, thanks Ken. Now for a couple new guy questions:

- Best place to get replacements? (I've used digikey in the past) I've bought the wrong components before, so any advice on specific part numbers or what to search for would be welcome. Helps me avoid over ordering when I get paranoid and think I've got the wrong part ha.
   For example, the large blown cap... never bought one that large. It says 470uF, 200WV, 85deg C. Diameter appears to be 22mm, height around 42mm. Would something like this work?
http://www.mouser.com/ProductDetail/Nichicon/UVK2D471MRD/?qs=sGAEpiMZZMvwFf0viD3Y3UC90LIngmp6xVvwqDKC7jE%3d
or
http://www.digikey.com/product-detail/en/200VXR470MEFCSN22X40/200VXR470MEFCSN22X40-ND/3565112


- Testing - Do I need to desolder everything for testing, or will on board work in most cases?

I appreciate everyone's patience  and advice as I learn more about this every day. If there's a how-to for testing that I miss please redirect me, I haven't found a good one yet. Thanks all!

[MaxAsh]

The exploded main filter capacitor will have to be replaced and I bet one or more of the four diodes next to it are shorted. Possibly a blown foil trace on the foil side of the board. Transistor Q801 is the B+ regulator and it should get tested to see if it's shorted along with transistors Q802 and Q803 (also part of the power supply circuit.

Four diodes next to the exploded main filter capacitor all test at 0.566, so seem to be okay. Transistors on the other hand, not so much. Q801 is coming up 0.511 on one outside leg, but no reading on the other outside leg at all. Q802 is reading 0.672 on one side and 1.070 on the other. Q803 is reading 0.511 on one side, and toning with 0.004 on the other. I'm assuming this means all three transistors (Q801, Q802, Q803) are all in need of replacement? Or is Q802 borderline? Quick shot of the backside of Q801 attached. I don't see any foil traces blown at a glance.

[MK3FAN]

I would remove all the transistors from the circuit to test them properly and avoid any erroneous readings that might lead you astray.

[MaxAsh]

I would remove all the transistors from the circuit to test them properly and avoid any erroneous readings that might lead you astray.

Okay, will do. I haven't had any luck finding a replacement tall white resistor. Can someone direct me to them at mouser or another site? Thanks EDIT: Found a picture I took of the chassis before that resistor popped, writing on the side was: 25W 140 ohm J.

Also, anyone have thoughts on the "isolation" transformer pictures/questions above? Still wondering if I can even re-wire what's shown, or if I need to buy another isolation transformer.

[MaxAsh]

I cannot for the life of me find a 25W 140 ohm resistor like the one I blew. I found a 25W 150 ohm on radio shacks eBay outlet, but that's the closest I've come. This is driving me nuts as I've never dealth with resistors like this one in the past.

http://www.ebay.com/itm/NE-25W115-25W-Cermet-Power-Wirewound-Resistor-150-Ohms-5-25W115-/360800801697?pt=LH_DefaultDomain_0&hash=item54016753a1#ht_1145wt_1105

My desoldering pump broke, new one arrives tomorrow so I'll be pulling components for additional testing tomorrow night. In the meantime, if someone has feedback on what to do with the transformer situation above, I'll work on that piece. Thanks all

[Ken Layton]

You'll probably have to use the 150 ohm 25 watt one. Mouser is out of stock of the only resistor close to the one you need and it listed as being another 12 weeks before they have one.

Digi-Key and Jameco don't even carry anything close.

[MaxAsh]

You'll probably have to use the 150 ohm 25 watt one. Mouser is out of stock of the only resistor close to the one you need and it listed as being another 12 weeks before they have one.

Okay, thanks Ken. As long as the 150ohm 25W one won't cause trouble, I'll give it a try. Any thoughts on the original cause of my problem? Just curious if I need to order an isolation transformer before going any further, or if I can use what I have and re-wire. Something about it all just seems odd.

[ed12]

10 ohms is not really that big of a deal
rember 140 ohm +/- 10%,
it is there as a dropper/in-rush limiter

ed

[MaxAsh]

Okay, thanks Ed12. Assuming no one has objections, while I wait for a few items to arrive in the mail I'm going to dismantle the entire power section and check everything. I assume I can just peel back the "paper" around the transformer to see how everything underneath is wired, correct?

I went through the wiring diagrams in the document Ken linked (Thanks Ken) and found the Power Wiring info shown in the attached picture. This is exactly how mine is wired... yet the consensus seems to be that this wiring is incorrect if the chassis requires isolation, am I correct? Would it make sense to just take the monitor off this transformer (leaving everything else the same), and just buy a new isolation transformer for $20 or so, place it next to this one and wire it solely for monitor?

EDIT: Adding image showing Transformer Chart. As you can see, the output of the transformer shows "120V Isolated for Monitor and Power Supply" (The Marquee Light Fixture is also coming out from that spot). All of my wiring exactly matches these two diagrams. Based on the above comments, this is what blew my new Chassis, correct? Is that's accurate, where do I go from here? Thanks again everyone, I know this thread has grown into quite a series of questions.

[MaxAsh]

Just found an older post from KenLayton about the same Midway wiring setup where he says you never unwrap the transformer, so I've left it alone. But that leaves me a little stuck as to my next step. If I can't rewire the transformer, which appears to be improperly setup for isolation, then I'm not sure where to go from here. Ideal situation would be I test/replace various parts on the chassis that blew, then hook it up and try again, but until I figure out the root cause of the initial blow and handle it, I'd just be wasting time/money on repairs. After a lot of success early in this hobby, I knew I was due for a bump in the road. Definitely frustrating, I would be going insane without you guys! Many thanks - let me know which steps to take next and I'll get on it asap.

[ed12]

with a meter
chk the primary blue and yellow to any lead on the secondary side
if u get counity then IT IS NOT AND ISOLATION TRANSFORMER,HOWEVER IF U DO NOT
THEN IT IS AN ISOLATION TRANSFORMER
also make sure to un-hook the transformer >any plug's going to it<
so u are chking the transformer olny,and do this with the machine un-plugged from any
power source

easy as pie

ed

[MaxAsh]

with a meter chk the primary blue and yellow to any lead on the secondary side
if u get counity then IT IS NOT AND ISOLATION TRANSFORMER,HOWEVER IF U DO NOT
THEN IT IS AN ISOLATION TRANSFORMER
ed

Just performed the test (hopefully correctly), see attached image. I checked all the purple (and for kicks the yellow) wires against the incoming blue/yellow connections on the other side. I placed one probe in the yellow connector pin and tested all the purple wires, then again on the blue pin. No continuity with everything unplugged.

Just so I'm certain I did this correctly, the wires I tested on the secondary side were the ones that connect to the blue/yellow wires from the cabinet switch going into the transformer, right? They actually change color from blue/yellow into blacks/whites as they go into the transformer (and the blue gets split a bunch of ways in the connector).Attaching a pic of the large connector when it is plugged in, just for clarity. Thanks for the patience Ed!

I also performed a Voltage test with the secondary side hooked up to power. Incoming from the cabinet switch I'm receiving 119.7 Volts going into the transformer, but on the other side all of the purple wires are testing as 131.4 Volts.

[ed12]

if u got no countiy between primary and secondary side
then it is an isolation transformer
117 in and 131 out = no seconday side load
that 131 will drop to 120 fast enough under load
btw just for refernce a smps power supply dose not require a isolation transformer
as it is already isolated by design,we just do it for good measure..
if u need rfernce to the ^^^^ statment i just made
look at any spms power sullp schmeatic
u will catch on fast to the fact..but as i said to avoid the aurgment
we do it for good measure..
so all that aside when u go to repower the unit
un-plug any and all marque light's as showen in ken's pix..
this way u ar truly isolated

ed

[MaxAsh]

So based on the test, it is an isolation transformer. And from what you said, the 131.4V coming out is okay. Sounds like the SMPS sharing the output with the monitor is okay from your comments as well. So the culprit would just be the marquee light? The really strange part is that the marquee light has no bulb, so it wasn't lit, not sure if that matters. Is it really possible that just because the unlit, unbulbed marquee shares the output with the monitor, it fried my chassis? Wow.

Is there anything else I should check? What about something being grounded, or not grounded, that should be? The only ground on the chassis that I recall connecting was the monitor strap over to the neckboard ground pin. I'm also wondering if part of the chassis might have been touching the metal monitor frame by accident. Just some random thoughts/questions.

[ed12]

wow my last post was classic case of slow down when typing >ed<
for good measure just un-plug any marques..
your chassic should have a green wire from the meatl pan to ground
ie 3rd wire >green< on a north american 120 volt system
again just good measure

ed

[MaxAsh]

your chassic should have a green wire from the meatl pan to ground
ie 3rd wire >green< on a north american 120 volt system
again just good measure
ed

Looked around the metal frame, look what I found. Chopped off ground wire, lovely. Sounds like this wouldn't have caused my problem, but it's something to keep in mind. So to sum up where I'm at, since this thread has gotten long:

1) Wired up chassis exactly as I saw it setup, however output from transformer is shared with Switching Power Supply and Marquee Light
2) Turned on cabinet, 5 minutes later smelled burning, felt extreme heat from large resistor area, then cloud of white smoke, shut everything down.
3) Found blown main large capacitor, cracked large resistor. Possibly blown transistors, though diodes near power supply test okay.

Things Tested/Discovered:

1) No continuity across transformer with everything unplugged.
2) 119.7V coming into transformer, 131.4V coming out when hooked to household power
3) Tested DC across transformer with 6V battery, DC does not pass through.
4) Marquee, Chassis and Switching Power Supply all share the same output terminals on the transformer
5) Marquee fixture was plugged in at the time of chassis blowout, but there is no bulb in it. Further inspection reveals the fixture looks broken/damaged.
6) Chassis frame not grounded
7) Cabinet is wired in old Midway style, exactly as shown in power wiring diagrams earlier in thread.

Probably a few other items, but that's the general idea. Thanks all for everything so far, you've been great! What's next?

[MaxAsh]

It's been suggested by a local tech that I may have let a portion of the chassis touch the metal frame of the monitor. I'm not 100% certain the chassis was properly mounted/separated upon reflection, so it's possible this is true. So my question would be: is it possible for a chassis to be improperly touching the metal frame, function for 5 minutes, then blow? Or would that be an instant burn out situation?

Thanks

PS - I'll be desoldering more parts and testing them tonight, so I'll post an update of the test results as soon as I have them.

[MaxAsh]

Okay everyone, here's where I'm at testing. Feedback is welcome, many thanks:

Q801 - Good (.511 and .548 readings)

Q802 - Good (Base to Emitter .699, Base to Collector .671)

Q803 - Bad (No readings and/or Tone on all measurements)

D801, D802, D803, D804, D810   Good (.500-.599 range)

R808, R809, R810   Good

We know large capacitor (C918) and resistor (R804) are blown

EDIT: Tested Q401, I think it's Bad (Base to Emitter .088 , Base to Collector 0.501) - this is way over by the flyback area

Attaching a pic of Q401 from the back, should it look this messy?

[ed12]

good measure say's replace it if in doubt.

the messy part u speak of is flux
left over from another replacement,
ie: the tech never used flux remover..nothing to worrie about

ed

[MaxAsh]

good measure say's replace it if in doubt.

the messy part u speak of is flux
left over from another replacement,
ie: the tech never used flux remover..nothing to worrie about

ed

Okay, thanks. Based on the original images of the board, is there anything else I should test? I could spend half the night desoldering everything, but the impression I got was that I should test the diodes/resistors near the power section, as well as all the transistors. I've done that, so should I be good to order the parts on the bad components, solder them on, and give it another try (after ensuring isolation again)? Just want to make sure I order everything in one batch if possible.


Thanks

[ed12]

i have a few q's,but i want some clearity on this statment
>It's been suggested by a local tech that I may have let a portion of the chassis touch the metal frame of the monitor<
how did this person deduce this information.?
the reason i ask is easy u touch any hot chassic to ground and u WILL have a very beautifull black mark
and a few blowen trace's,plus a black mark on the chassic pan..is this what u are seeing ?
if  not it was not isoalted right,at which point i would worrie about the mother board >game-board<,
at this point is wish u had a varic..but i will hand u a piece of advice
60 watt light bulb >yes real bulb<,it is to used as a fuse,reason is if u have problem we can better save u the money on another set of part's.
the bulb replace's the main fuse for the time beenin

ed

[MaxAsh]

I'll do my best to answer, thanks Ed

i have a few q's,but i want some clearity on this statment
>It's been suggested by a local tech that I may have let a portion of the chassis touch the metal frame of the monitor<
how did this person deduce this information.?

While speaking with him on the phone, he asked if I had properly secured the chassis to the frame and ensured no metal was in contact with the chassis that shouldn't be. I had not fully secured the board, but it was resting on the plastic mounting stands all over the frame. He said he blew out a board once by letting it touch the frame, so he thought it was a possibility.

the reason i ask is easy u touch any hot chassic to ground and u WILL have a very beautifull black mark and a few blowen trace's,plus a black mark on the chassic pan..is this what u are seeing ?

No, no black marks or blown traces, and the damage happened after about 5 minutes of running. The resistor/capacitor gradually got hotter and hotter until there was a blow (from what I could tell). Sounds like the chassis wasn't touching the frame based on your comments. That's a good thing.

if  not it was not isoalted right,at which point i would worrie about the mother board >game-board<

Game still plays fine blind, no issues from what I can tell. I have a Hantarex Polo 25 that I'm told requires no isolation, I could hook it up again to test it if you want.

at this point is wish u had a varic

Not sure what a Varic is... maybe Variac? If so, I don't have one no sorry 

..but i will hand u a piece of advice 60 watt light bulb >yes real bulb<,it is to used as a fuse,reason is if u have problem we can better save u the money on another set of part's.
the bulb replace's the main fuse for the time beenin

Sorry, you lost me a bit here. Not sure what you're suggesting, don't forget I'm a noob still learning this stuff. I've seen a bulb trick used in TV repair in place of a resistor, but that was once long ago. If you could clarify that would be great.

As for parts, here's what I ordered so far:

(1) 25W, 150 ohm resistor to replace the tall white one that blew/cracked. The original was 25W, 140ohm, but I'm told this one is okay. It arrived today, cost $1.29
(1) 470uF, 200V capacitor to replace the main cap that blew
(1) C5296 Transistor to replace Q401, which tested bad
(1) C2688 Transistor to replace Q803, which tested bad

So far that's all I ordered. Everything else I tested (diodes, resistors, etc) all came up good after I removed and tested them. I only tested the components around the power/flyback areas.

My plan is to reterminate the Marquee and Switching PS to the incoming AC (taking them off the transformer). This will leave only the chassis power supply coming off the transformer on that side at the top (the 6V to coin door will still be on that side, but on the bottom from what I can tell). Is it okay if I just cut and cap the wires going coming off the transformer to the Marquee and Switching PS for now, and re-terminate them incoming AC using new wiring?

[ed12]

the answer to the bulb question is it goes in place of the fuse >main fuse<
it act's as a load,if it light's bright = dead short..simple.. if it is dim
then it is under load..save's replacing a wack of part's

so in short u solder 2 wire's to the bulb
1=outside ring
1=center tab
solder to the fuse holder
u are gold....

ed

[MaxAsh]

Waiting for the components to arrive. In the meantime, I've been trying to tackle the isolation transformer situation. I mentioned previously that the output seemed high. It was suggested I test it under load to see what happened. Here are some test results, please let me know if this seems odd:

Isolation Transformer Output tests:

Zero load = 133.6 V
Hooked up 13" old CRT TV/VCR to it = 132.1 V
Hooked up TV above and a large fan = 131.2 V

Would I need a much heavier load item? Or is this proving the output is too high? Thanks for any advice, just trying to figure out if I should buy a new ISO or not.

[ed12]

120 +/- 10% =130 or 110
u olny have 1 of the secondary's loaded,so i would expect it to be a tad high

ed

[MaxAsh]

120 +/- 10% =130 or 110
u olny have 1 of the secondary's loaded,so i would expect it to be a tad high

ed

Okay, thanks ed. I just wanted to make sure before I keep going. I think I'm going to swap the Hantarex Polo 25 I have over to the MK cabinet, and then continue to work on repairing this one in the less-important Time Killers cabinet. Based on what I've read, the Hantarex Polo 25 doesn't require isolation (though I'll still rewire the MK cabinet anyway just in case). This will give me a functioning Ultimate Mortal Kombat 3, and a project with the Time Killers cabinet (which is fine, because I'm probably going to MAME it eventually anyway). Any objections to that plan? If not, I'll go with that, and come back here with advice as I work on the busted chassis.

[ed12]

no by all means get to gamming

ed

[MaxAsh]

no by all means get to gamming

ed

Swapped the Hantarex Polo 25 with the broken Wells G monitor. I've had it hooked up and running now for 30+ mins, no major issues. Two things popped up, but seem to be okay:

1) After first hooking up the monitor, the controls all went dead. That seemed really odd. I adjusted a couple of wires, thinking perhaps something was loose, and that seemed to do the trick. Strange, perhaps I bumped something. Been good ever since.

2) The image was a little off at first, but I made some adjustments. I saw some retrace lines, so I turned the brightness down. That seemed to help, but I noticed the screen will randomly "brighten" now and then, going back to the correct darkness level shortly after. I'm not sure if that's just a wobbly/dirty/lose pot for the brightness adjustment or something else. I used the flyback brightness, as the remote adjustment didn't do much.

Overall, looking good. Attached a pic for reference. Any issues, I'll update. Once I get the parts for the blown chassis, I'll come back for some advice on repairing it. Thanks!

[ed12]

u might as well add some control cleaner to your order
this way u can spray down and clean them dirty control's proper like

ed

[MaxAsh]

u might as well add some control cleaner to your order
this way u can spray down and clean them dirty control's proper like

ed

I've got some Control/Contact cleaner & lubricant spray from radio shack. It's probably 6 years old, but I doubt it expires. I'll test it out, thanks for reminding me I had it!

I noticed that the Sync pin on the RGBGrSync connector plugging into the chassis is loose. The connector pin itself is beat up/twisted from being removed and reinserted. I want to replace the connector and grab new pins, but it's expensive (shipping-wise) to order just that from mouser. The connector + pins are probably $1 or so, but the shipping is minimum $5 most places. I tried eBay, no luck so far. Anyone know where I can snag a normal 6-pin RGBGrSync connector and half dozen pins for a couple bucks? Would a local store have them? I know they often have bigger molex connectors, but I've never seen these smaller ones. If someone has a pile of connectors and pins lying around, I can paypal them a couple bucks if they'll toss 'em in an envelope 

[MaxAsh]

Ken - for reference from our conversation, see attached pics of the existing RGB connection to the chassis. I attached a shot from both sides in case you wanted to see the traces from the reverse. As you'll note, there appears to be a 6-pin position squeezed in next to the 5-pin they automatically give you. Based on the board layout, I'm assuming I remove the 5-pin and put the 6-pin I ordered in the position adjacent to it. Seems like common sense, but given that I've blown the board up once, I wanted to double check.

Thanks!

[Ken Layton]

Yes, the new 6 pin will be placed in the 6 position holes which are to the right of the 5 pin holes. The "locking ramp" of your new 6 pin header (if it has a locking ramp) will face the 3 black electrolytic capacitors directly to the left of the connector.

I would connect the harness composite sync wire to pin 5 of the new connector.

[MaxAsh]

Yes, the new 6 pin will be placed in the 6 position holes which are to the right of the 5 pin holes. The "locking ramp" of your new 6 pin header (if it has a locking ramp) will face the 3 black electrolytic capacitors directly to the left of the connector.

I would connect the harness composite sync wire to pin 5 of the new connector.

Great, thanks Ken, will do. After this I'm just waiting on one transistor that for some reason got stuck in FL for 4 days during shipping. Going to work on cleaning up the isolation transformer wiring.

My plan is to test-bench this setup this time around, instead of trying to just setup the chassis inside the cab. Aside from the AC power, isolation transformer, chassis/monitor... is there anything else I would need just to test the chassis portion? Could I essentially just set the monitor/frame/chassis on the workbench, set the power block and isolation transformer on the bench, hook it up to power, and fire it all up? The reason I ask is because the power coming from isolation to the chassis has no ground wire in this setup, meaning the only "ground" setup on the chassis/monitor will be the wire-wrap around the monitor going to the neckboard. That just seemed odd to me. Thoughts? Setup would look like this:

• AC (w/ ground) -> Isolation -> 2 wires (no ground) to chassis
• Neckboard in place with ground wire-wrap from tube on it
• Anode in place
• no ground on monitor frame

Just feels like something will be hot that I don't want in that scenario, so I welcome input, thanks. Assuming the monitor-only test goes well, I'd try it with the PCB, etc hooked up next, adding in each item one at a time.

[ed12]

all them green wire's should be your earth ground
and at least 1 of them will find it's way to the chassic of the power transformer..
as for the power supply,there will a post marked :fs:,that is the earth ground,
as to the monitor chassic that spot u posted the picture on is your earth connector point

ed

[MaxAsh]

all them green wire's should be your earth ground
and at least 1 of them will find it's way to the chassic of the power transformer..
as for the power supply,there will a post marked :fs:,that is the earth ground,
as to the monitor chassic that spot u posted the picture on is your earth connector point

ed

Hi ed - I got a little confused by your post. The power block itself is grounded of course, as are most connections in the cabinet. The power going to the chassis isn't, because the Wei Ya only has AC 2-wire coming off the board, not a 3-wire with ground. Using Ken's directions, I cut the AC cord on the chassis and added a regular 2-pin connector so I could plug it into the existing power. Here are some pictures that should help. I'm thinking the picture you're referring to was the one from post #32 in this thread, where I posted an image of a ground wire on the side of the monitor frame that was cut sometime by a previous owner? In any case, here's the setup. One pic shows the power "block" where you see the incoming AC (filter, fuses, etc under the metal casing). On top of that, bolted to the metal casing, is the transformer. I see tons of ground wires coming off the top of the metal casing, none of which go to the transformer, but the fact that the transformer is bolted to the metal casing, which is grounded, makes me thing I'm good there. The second pic shows the 2-wire power plug coming off the chassis, as well as the neckboard where I connected the monitor's wire-wrap ground strap cable.

I just thought it was weird that the chassis power has no ground, and the frame's ground wire was cut as well. I can re-wire the missing frame-to-ground connection for safety purposes. But am I okay with the incoming power to the chassis being ungrounded?

[ed12]

picture #3 is what i am refering too

>I can re-wire the missing frame-to-ground connection for safety <

just do that part
and u are gold

ed

[MaxAsh]

picture #3 is what i am refering too
>I can re-wire the missing frame-to-ground connection for safety <
just do that part
and u are gold

ed

Okay, cool, will do. Now I just stare at the mailbox until the last transistor arrives. I finished rewiring the isolation transformer to remove the marquee and switching PSU from the same output as the chassis power. I'm basically ready to test as soon as I solder on the last component. Come on mail... hurry up

[epicfatigue]

Sounds like you have two of the best people helping you with this should have it fixed in no time.

As for the light bulb in series with the fuse this is kinda what they are talking about if you want a visual this is one i built (half finished in this pic)
That does 240/110 and has a range of watt globes that can be switched between then completely cut off for quick testing i made for my little workshop.




Good luck with the repair!

[MaxAsh]

Nice, thanks for the visual!

Still waiting on the last transistor... it left FL a few days ago. In the mean time, working on the MAME build.

[chiemgau1]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

[MaxAsh]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

Do you mean the corrected wiring (changing the transformer to normal isolation setup) or the original Midway cabinet wiring? If you mean the original, I posted a diagram from the service manual a ways back in the thread. If you mean the way I re-wired it, I basically just removed the Marquee Light and Switching PSU from the transformer output terminals and changed them to direct from AC. I can draw up a sketch, which would be cleaner than the pics of the actual wiring, if that would help. Let me know.

[MaxAsh]

UPDATE: I finished replacing the friend components on the Wei Ya chassis. After some thorough pre-hookup testing, I went ahead and setup everything on a test bench and gave it a try.

First, the good news: It powered on, and the game displayed on the screen immediately. Looked good too, better than my original attempt before the chassis blew. No sync issues either.

Now the worrisome news: I think something is about to go again, so I turned it off. Looking for some thoughts/advice. Here's what happened...

I left it running and continued to observe and check heat levels on components. Last time it blew, I felt a large amount of heat coming off the tall white resistor (25W, 140ohm). I smelled "burning" and then that resistor cracked/blew and produced an ominous white cloud. This time, that resistor is nice and cool, no issues, looking good. Unfortunately, the resistor immediately next to it (labeled 5W 2.2ohmJ) is giving off a LOT of heat, and is very hot to the touch. I'm starting to smell a similar scent to the one I did previously when I lost the larger resistor. I shut everything down as a precaution. Should I just fire it up again and let it run, see if something cooks? I let it go for 4 minutes before the heat seemed too high and I started to catch a smell. Last time, when the big one blew, it was after about 5-7 minutes of running time.

Thoughts? I know some heat on a resistor is okay, but I can't keep my finger on it for more than a second or so without having to remove it, which sounds hotter than I'm used to feeling on a resistor. See attached pic of the resistor.

Quick Edit: Tested power at chassis, still showing around 131 V while running. I know previous replies said this is okay, but we're certain that's not cooking things?

[chiemgau1]

Could you post some pictures of all the cabinet wiring.
I am in the same position as you are... Same monitor, same game, same cabinet just a nba jam setup at the moment.
Just need to get the monitor chassis and set up the wiring to work for UMK3.

So I'm following your posts.
Thanks

Do you mean the corrected wiring (changing the transformer to normal isolation setup) or the original Midway cabinet wiring? If you mean the original, I posted a diagram from the service manual a ways back in the thread. If you mean the way I re-wired it, I basically just removed the Marquee Light and Switching PSU from the transformer output terminals and changed them to direct from AC. I can draw up a sketch, which would be cleaner than the pics of the actual wiring, if that would help. Let me know.

The cabinet I have is NBA Jam but most of the wiring has been removed. The tube from the monitor with no chassis the power supply wiring as well as the iso transformer are still hooked up but that's about it. So I was just wondering if you could post a few pics of the inside because I want to see how it's wired up. I got the wiring for the joysticks and buttons from the machine the UMK3 board come out of but it's a mess right now. Thanks

[MaxAsh]

Sure, I can pop it open and take some pics of various wiring sections.

Anyone have feedback on the last post I made about the overheating 5W resistor?

[MK3FAN]

Sure, I can pop it open and take some pics of various wiring sections.

Anyone have feedback on the last post I made about the overheating 5W resistor?

Glad you got it running again. As for your overheating resistor, it might be normal. There are some resistors on the K7000 that get extremely hot also. I forget, are you running this chassis through an isolation transformer? If so, is it funtioning and hooked up properly?

[MaxAsh]

Glad you got it running again. As for your overheating resistor, it might be normal. There are some resistors on the K7000 that get extremely hot also. I forget, are you running this chassis through an isolation transformer? If so, is it funtioning and hooked up properly?

It appears to be an isolation transformer, but for whatever reason midway used to wire them so the switching power supply, marquee light, and monitor all came of the same side. I re-wired it so the light and switching power supply are coming off the AC power/ filter area instead, and just the monitor chassis is on the transformer now. Both cabinets I have are wired this way, and both seem to output around 131V on the transformer output. I'm told this is because back when they were manufactured, household current wasn't consistently 120V range like it is today?

I tested the transformer using instructions I found online, which basically tested to make sure no DC current was coming through, and normal transformer functionality was indicated by the tests.

So that resistor being really hot, and starting to smell, is okay? It sure smelled like burning to me, which happened just before the big resistor blew. Maybe I'm just paranoid?

[MK3FAN]

Hell, is shouldn't be melting of course but a lot of times, the factory puts a coating on those resistors and the smell is the coating being burned off. In my personal opinion, I'd say you're probably ok using it.

[MaxAsh]

I guess I could just leave it running and cross my fingers. Last time it made it a little over 5 minutes. So far I've gone 4 minutes since I replaced the blown components, smelled bad things/felt heat and shut it down. I guess at this point, worst case it blows again. Technically, I don't "need" the monitor since I swapped the Hantarex I had into the UMK3 cabinet, and then converted the cabinet I pulled it from into a MAME with LCD.

Basically, I have a monitor/chassis on my work bench hooked up to a Time Killers PCB that I don't really need. Ideally I'd sell it, or better keep it for another cabinet project. So... I guess if it blows, I just call it a day. Deep down I just don't want to admit I may have wasted $95 on a chassis, I want to see that thing work like a charm and feel good about it. After you blow it once, you want it to work the second time haha. Well... maybe I'll give it a try. Gulp.

[Ken Layton]

I'm looking at the power supply section of a schematic to a model 825 Wei-Ya. The 2.2 ohm 5 watt resistor is connected in series with the 140 ohm 25 watt resistor. Looks to me like it's supposed to get hot.

[MaxAsh]

Okay, Thanks Ken and MK3fan, I guess it's time to go for it. I've done everything recommended and tested everything suggested. I'll plug it all in and let it ride. I'll let everyone know how it goes.

Thanks to all for the advice and assistance! Either way, regardless of if this works, you've all been awesome.

[boostin4hp]

I have the same configuration and problem with sync. Did you ever get this running again and fix the sync issue?

[MaxAsh]

I have the same configuration and problem with sync. Did you ever get this running again and fix the sync issue?

I haven't had a chance to set it up and let it run to see if it has another meltdown. Part of me has been avoiding it, but mostly I've just been busy working on another project. As for the Sync issues, I'm guessing you're referring to something from earlier in the thread. The two things that fixed it were:

1) Americanize the Wei Ya Chassis (search for Ken Layton's post on it, very informative). One of the key points from that process is changing out the Wei Ya's 5-pin RGBGrSync connection for a standard 6-pin one.

2) Making sure my sync pin was in the correct place. The game I had, for whatever reason, had the sync pin setup for pin 5 instead of pin 6. I just had to move it to the other position to fix the sync issues.

Hope that helps! I'll report back when I setup my test bench and try out the chassis/monitor again for a full, long-term test.

[MaxAsh]

Good news, followed by some seemingly very bad news:

Setup everything on the test bench, wired it all up, turned on the game. Looked excellent, colors, brightness, you name it, perfect. Ran it for just over 2 hours to ensure it was working great, no issues. I proceeded to mount everything, making sure it was all properly wired, hooked up, etc. Plugged in the cabinet, turned in on, worked great. Ran it for about 10 minutes, no issues. This is where things suddenly went bad:

My back is to the screen as I'm looking at something else and I hear what sounds like "scrambling". Not sure if you know what I mean, but basically that sound a CRT TV/Monitor makes when the image suddenly goes all wacky. I turn around and see that the image is basically a wash of rainbow colors, no coherent image. Looks all crazy for unknown reasons. I attempt a couple of adjustments, nothing helps, so I turn it off. I checked everything, looked okay, so I turned it back on. This time the screen stays almost completely dark. There's not "static" on the screen when I touch it like usual, but I have neckglow. Every 30 seconds or so, I see a little flicker of light randomly on the screen, then blackness again. Nothing appears to have blown this time, but I'm back to a dead screen. No idea what I did or what went wrong. After 2+ hours of great functionality, I'm at a loss. Ugh.

[grantspain]

disconnect your video signal and then turn the screen volts adjustment on the flyback and hopefully you will get a raster,if you do get a raster then the issue will be related to power supply dc voltages or your game board

[MaxAsh]

disconnect your video signal and then turn the screen volts adjustment on the flyback and hopefully you will get a raster,if you do get a raster then the issue will be related to power supply dc voltages or your game board

Game works perfectly on another monitor, but I'll go give that a try and report back thanks

[adidas1984x]

any updates??

[MaxAsh]

any updates??

Sadly I've had zero luck after the monitor died a second time. Really frustrating to go through everything, get it working for a couple of hours, then suddenly have it go out again. I'm fairly certain the original crash and burn was because of the incorrectly setup isolation transformer the cabinet had in place. The second was probably a damaged or weakened component from the first blowout that didn't get replaced in my fix. Not really sure.

I've put it off to the side to give me space to work on several other arcade-related projects. I sold the UMK3 cabinet with a different 25" monitor in it, so I don't have UMK3 to test it on anymore. I do have a Street Fighter II World Warrior... not sure if there would be an issue using a 25" monitor with that? If it would work, I could try testing on that too when I have time.